ISDN: a snapshot

Abstract

A snapshot of the present status of ISDN (integrated services digital network) is presented in terms of standardization efforts, field trials and demonstrations, implementations and services, and equipment and devices. A review of opinions and controversies as well as future trends is also given. The authors emphasize the importance of the worldwide standardization effort and discuss the organizations that are responsible for establishing such standards. It is pointed out that, with the limitation and inflexibility of the narrowband ISDN and the broadband ISDN, issues for higher-rate services have become prominent. For broadband services, the problem is not merely increasing the speed of the operation. It affects the compatibility of switching technology, the workability of the local loop arrangement, the availability of rate adaption, and the efficiency of bandwidth utilization. Although some basic principles of narrowband ISDN can be carried to broadband ISDN, the technology is quite different. For example, the interconnection and transmission problems of video, HDTV, (high-definition television), and high-speed data are different from those of voice. Thus, the standard 64-kb/s B channel itself, the fundamental rate of ISDN transmission, appears inadequate for wideband services. At present, the solution is to establish the multiples of 64 kb/s for accommodation of broadband or higher rates.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>